Automatic flash equipment has been developed wherein the amount of light supplied by the flash is determined by range, which is a combination of the reflectivity of the scene together with flash to subject distance, camera aperture, and film speed. In such equipment the flash tube is turned off, or quenched, when sufficient light has been reflected from the scene for the selected aperture and film speed. One such automatic flash is disclosed in U.S. Pat. No. 3,809,951.
More recently, similar automatic flashes have been developed for use with automatic exposure cameras such as the Canon AE-1, the Olympus OM-2 and others. Examples of such systems are disclosed in U.S. Pat. Nos. 4,047,194; 4,079,385; 4,078,242; and 4,095,242. Such flash systems are usually dedicated for use with the particular camera, and operate in conjunction with the exposure control system of the automatic exposure camera, and more usually a shutter-preferred automatic exposure camera, to determine the amount of light to be supplied by the flash. In general, the dedicated flash provides a signal to the camera which causes the camera to automatically pre-set the aperture, and the flash, when fired, supplies only the amount of light appropriate for that aperture. Also, the dedicated flash provides a ready signal which causes the camera to set the shutter to a flash synchronization speed. However, it has thus far not been possible to operate the dedicated flash remotely from the camera in conjunction with the exposure control system of the camera, while sensing the amount of reflected light received at the camera.
Thus far, however, it has not been possible to use a conventional automatic flash in conjunction with the automatic exposure feature of such cameras. Thus the purchase of such an automatic exposure camera has required the purchase of an associated, dedicated flash, or the use of the automatic exposure camera in a manual mode with a conventional automatic flash. There has therefore been a need for a means by which conventional automatic flash could be adapted for use in conjunction with the exposure control system of an automatic exposure camera, and which would permit off camera operation while still sensing the amount of reflected light received at the camera.